The present invention relates to a process control system and a process control method that may be adopted to implement control on processes through which semiconductor devices, for instance, are manufactured.
In a semiconductor manufacturing factory, for instance, a plurality of process units are installed for semiconductor production. Each process unit includes a transfer apparatus that transfers workpieces such as semiconductor wafers (hereafter to be referred to simply as “wafers”) to a plurality of processing apparatuses such as etching apparatuses. In such a process unit, wafer processing is executed in a specific sequence while transferring the wafers to the individual processing apparatuses. Test wafers are normally used to regularly check the quality of process result in the etching apparatuses or the like. These test wafers undergo the processing mentioned above and then the etching rate, across wafer uniformity and the like of the test wafers having undergone the processing are inspected by employing inspection device. A judgment is made as to whether or not the processing should be continuously executed based upon the inspection results.
The inspection devices are usually installed in a separate room from the room where the process units are installed. In addition, while there are various types of inspection devices, some test wafers may not always undergo all types of inspection. However, the utilization schedules of these inspection devices are not well organized, resulting in some test wafers being left in an inspection wait state for a considerable length of time. In addition, when test wafers are used to check the states of the processing apparatuses in correspondence to individual processing steps, the test wafers cannot be transferred to the processing apparatus which executes a different processing step until the inspection for the current processing step is completed. Thus, it takes a considerable length of time to process the test wafers, leading to lower operating rates of the processing apparatuses. It is to be noted that examples of the related art in which the inspection devices are installed together in a room separate from the room where the process units are installed include the technology disclosed in Japanese Patent Laid-open Publication No. 9-22306.
In another example of the related art, which is disclosed in Japanese Patent Laid-open Publication No. 10-12694, an inspection transfer path is set up for test wafers in addition to a production transfer path on which production wafers used to manufacture regular products are transferred, so as to transfer the test wafers through the inspection transfer path when conducting inspections. In this case, a greater area in the clean room needs to be allocated for the installation of the two separate transfer paths, one for the production wafers and the other for the test wafers, and the wafers cannot be transferred quickly.